Study and exploitation of bacteriophage encoded endolysins and expolysaccharide depolymerases.

Bacteriophages (or phages) are widespread viruses which infect bacteria. They use refined and highly adapted mechanisms to hijack the bacterial cell, which is subsequently used for the phage's replication. Unraveling the underlying fundamental processes and interactions between phage and host cell constitutes a corner stone in fundamental molecular research and served as a base for numerous applications. During the replication cycle, phages cross different barriers such as the peptidoglycan and biofilm matrix. Phages encode a diverse set of hydrolases to degrade these polymer structures. These enzymes are optimized by endless adaptive co-evolution between phage and host cell in order to function quickly, efficiently and with high specificity. Hence, these hydrolases are an attractive research topic to combat the different barriers posed by bacteria. Phages cross the peptidoglycan barrier twice, once during infection and once during lysis of the host cell. Therefore, they encode a distinct peptidoglycan hydrolase for each step, accompanied with its specific properties. Eight different peptidoglycan hydrolases encoded by Pseudomonas aeruginosa and Staphylococcus aureus have been extensively characterized on a biochemical, molecular and structural level. Furthermore, their potential as enzybiotics (the use of enzymes as antibiotics) to treat P. aeruginosa or S. aureus infections has been assessed. Different bacteria form a biofilm structure which constitute a possible obstruction for the successful application of peptidoglycan hydrolases as enzybiotics. Furthermore, biofilm formation causes problems in numerous other fields (e.g. silting up industrial pipes, blocking of catheters, increased resistance to antibiotics,..). The strategy used by a phage to circumvent this barrier is considered in this project. Aims: 1. General characterization and preclinical evaluation of P. aeruginosa and S. aureus bacteriophage encoded peptidoglycan hydrolases and their chimeric combinations as enzybiotics. 2. Identification of biofilm degrading P. aeruginosa phage proteins and peptidoglycan hydrolases originating from phages which infect Enterobacteriaceae or other Pseudomonads. The ultimate goals is to create a multi component system which combines the best of phage encoded hydrolases to combat bacterial pathogens.

Keywords:Peptidoglycan, Exopolysaccharide, Depolymerase, Enzybiotic, Biofilm, Endolysin, Bacteriophage

Disciplines:Microbiology, Systems biology, Laboratory medicine, Biochemistry and metabolism, Medical biochemistry and metabolism